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A TEXTBOOK OF PHYSIOLOGY 



unable to record faithfully the actual systolic and diastolic varia- 

 tions of pressure. To effect this record, delicate spring manometers 

 of rapid action and small inertia have been invented (Fig. 93). The 

 sphygmoscope consists of the finger of a rubber glove drawn loosely 



FIG. 93. KURTHLE'S SPRING MANOMTTB. 



FIG. 94. SPHYGMOSCOPE. 



so as to leave an air-space over the end of a rubber cork and enclosed 

 in a glass tube. The finger stall acts as a spring and the tube is 

 connected with a recording tambour (Fig. 94). A mercury manometer 



FIG. 95. TE ABMLET SPHYGMOMETER. (Leonard Hill.) 



The arm is slipped through the armlet, and the latter fixed round the upper arm by 

 drawing the straps tight. The armlet should be placed at the same level as the 

 heart. The syringe bulb is then rhythmically compressed, while the radial pulse 

 is felt. The height of the mercurial column is noted at which the pulse just fails 

 to meet the wrist. The screw valve attached to the syringe bulb is opened, and 

 the pressure allowed to fall gradually, a reading being taken at the moment when 

 the pulse again reaches the wrist. 



provided with maximum and minimum valves has also been employed 

 to indicate the maximal systolic and minimal diastolic pressure. 



For determining the arterial pressure in man, the apparatus used 

 is known as a "ephygmometer," or " sphygmomanometer." This con- 



